A few hours after President Trump attacked CNN chief White House correspondent Jim Acosta as “rude” and “terrible” during a press conference, network president Jeff Zucker told employees that CNN stands behind them.

“I want you to know that we have your backs,” Zucker said in the memo, which was obtained by The Hollywood Reporter. “That this organization believes fiercely in the protections granted to us by the First Amendment, and we will defend them, and you, vigorously, every time.”

Trump, and his spokesperson, White House press secretary Sarah Huckabee Sanders, have long insulted Acosta, but the president’s attack on Wednesday was his most personal yet.

“CNN should be ashamed of itself having you working for them,” Trump told Acosta. “You are a rude, terrible person. You shouldn’t be working for CNN. You’re a very rude person. The way you treat Sarah Huckabee Sanders is horrible. You shouldn’t treat people that way.”

In the memo, Zucker said, “The work that you do is important. It matters. And that is why we are so vigilantly protective of our role as journalists.”